Catalysts which can isomerize and metathesize olefins are of great commercial importance, since, among other utilities, this reaction makes possible the production of olefins in desirable molecular weight ranges from olefins in undesirable molecular weight ranges.
Unfunctionalized olefin isomerization/metathesis is practiced commercially and is traditionally carried out in two steps (G. W. Parshall and S. D. Ittel Homogeneous Catalysis, Second Ed., Wiley, New York, 1992, Chapter 4.3). The present invention carries out the same chemistry in one step. Catalysts which can isomerize/metathesize functionalized olefins are also of potential commercial importance, since they make possible the synthesis of chemical feedstocks from highly functionalized biomass.
Much is known about ring opening metathesis polymerization of cyclic olefins catalyzed by iridium complexes. These are summarized in the book K. J. Ivin Olefin Metathesis, Academic Press, London, 1983, Chapter 2.6.3. However, there are very few references in the literature to acyclic olefin metathesis catalyzed by iridium. Porri et al., Die Makromolekulare Chemie 1974, 175, 3097, and Porri et al., Die Makromolekulare Chemie 1975, 176, 3121, describe a catalyst system [Ir(COE).sub.2 Cl].sub.2 +AgO.sub.2 CCF.sub.3 +CF.sub.3 CO.sub.2 H effective for the ring-opening metathesis polymerization of cyclopentene, cycloheptene, and cyclooctene, and isomerization/metathesis of 1-pentene. However, unlike Applicants' system, the Porri catalyst system: (1) requires the presence of CF.sub.3 CO.sub.2 H; (2) discloses a AgO.sub.2 CCF.sub.3 to [Ir(COE).sub.2 Cl].sub.2 ratio of 2 to 1; and (3) is formed in a two-step process. Additionally, in contrast to Applicants' disclosure, Porri's system is not disclosed for the metathesis of functionalized olefins. Further, in one embodiment of the present metathesis method, Applicants have observed that the extent of isomerization accompanying the metathesis reaction is greatly reduced due to pre-incubation of the catalyst components prior to addition of the starting olefin compound.
Much is known about metathesis of acyclic functionalized olefins using catalysts based on molybdenum, tungsten, rhenium, and in some instances ruthenium. These are summarized in J. C. Mol J. Mol. Catal. 1991, 65, 145 and K. J. Ivin Olefin Metathesis, Academic Press, London, 1983, Chapter 8. The disclosure of methyl oleate metathesis in the present invention is the first example of acyclic functionalized olefin metathesis catalyzed by an iridium based catalyst.
Other references which discuss related systems are Rossi et al., Tetrahedron Lett. 1974, 11, 879 and Bianchi et al., J. Organomet. Chem. 1980, 202, 99. Rhodium catalysts which can simultaneously isomerize and metathesize acyclic olefins are disclosed in Hughes et al., U.S. Pat. No. 3,721,718.